(a) Field of the Invention
The present invention relates to a fuel injection device for internal combustion engines, and more particularly it relates to a fuel injection device of the suction pipe type or the distribution type in which fuel is intermittently injected.
More specifically, the invention relates to a fuel injection device arranged so that the output from a flow measuring device which directly measures the total amount of fuel to be sucked into an internal combustion engine is uniquely associated with the flow control of the injection device.
(B) Description of the Prior Art
Various fuel injection devices of the distribution type for internal combustion engines have heretofore been developed and put into practical use. FIG. 1 illustrates a distribution type fuel injection device for internal combustion engines which has a close connection with the present invention and whose construction has the following features.
(1) A rotor a is in the form of a cylinder having a pressurized fuel inlet b at one end thereof, the other end being closed, and a triangular window c formed in the outer surface thereof. PA1 (2) A sleeve d is fitted on the rotor a and has as many circumferentially equispaced orifices e as the engine cylinders, said orifices being disposed at positions associated with the triangular window c of the rotor a. PA1 (3) A stator f is provided with window openings g at positions associated with the orifices e in the sleeve d, each window opening g being connected to an injector attached to the suction manifold for the cylinders.
The device shown in FIG. 1 operates as follows.
Fuel pressurized to a fixed value is fed to a cavity h in the rotor a. The rotor a is driven at half the rotational speed of the crank shaft of the engine. Upon rotation of the rotor a, the triangular window c passes the orifices e one after another, so that pressurized fuel is fed to the injectors through the orifices e. If the value opening pressure of the injectors is maintained at a fixed value, the difference in the pressures which exist on both sides of the orifices e is constant, and the amount of fuel passing therethrough is directly proportional to the length of time for which an orifice e is exposed to the triangular window c. In other words, the amount of fuel to be injected at a time is inversely proportional to the r.p.m. of the engine. Further, the sleeve d having orifices e is axially displaced in connection with the amount of air sucked into the engine in such a manner that when the amount of fuel is large, it is moved to the left and when the amount of fuel is small, it is moved to the right. Therefore, it follows that the amount of fuel to be injected at a time increases or decreases in relation to the amount of flow of air. Thus, when the rotor a is rotated at half the speed of the crank shaft of the engine, fuel is injected into individual cylinders once every two revolutions of the crank shaft, the amount of fuel to be injected at a time being proportional to (total amount of fuel)/(r.p.m.) and hence to the amount of air to be used at a time. This device is characterized in that the operation (total amount of suction air)/(r.p.m.) and the fuel distributing and metering function, which are necessary for fuel injection devices of the intermittent injection type controlled by the amount of flow of suction air, are performed by a single mechanism.
The device described above, however, has the following disadvantages: The presence of the two fitting regions between the rotor and the sleeve and between the sleeve and the stator entails the danger of fuel leaking through such regions, causing an increased error of metering. Further, the device has three members which require high machining precision. They are the rotor, sleeve and stator, all of which require a very close tolerance. As a result, much time is required in machining these three members.